This invention relates generally to filters and particularly to filter systems for use in purifying fluids used in power generation plants. Fluids are used as coolants and to generate steam from the heat of the power generating reaction taking place in the power plant. Water is commonly used as a fluid in such power generation plants. Generally, to optimize the efficiency and performance of the application utilizing the water or other fluid, it should be purified, and filtering is a common means of purification.
Purification is typically completed in a system such as a large filter vessel containing multiple filters. This stage of purification is important, because any minerals or other impurities present in the water can foul the power plant by bonding to metal or concrete surfaces, reducing the efficiency of the plant and eventually causing damage that may require repair. Accordingly, the removal of impurities can directly affect the efficiency of the plant, and can assist in avoiding down time due to repair or cleaning. For example, if the water will be used to cool a reactor and generate electricity as it is passed through a steam driven turbine, it is important to remove any impurities within the water to prevent them from fouling the system and decreasing its efficiency. Minerals within the water may bond with the water conduit as it is subjected to heat, thus restricting the flow of water.
A typical purification system involves a large filter or demineralizer comprising a multitude of individual filters through which the coolant is passed. Previous methods of incorporating individual filters into a purification system have failed to address the problem of individual filters becoming detached from their connections within the purification system, thus allowing impurities to enter the power plant, and eventually causing the power plant to be shut down pending the reconnection of the filters. These filters are often connected with hook and guide rods which require a great deal of force to latch the spring loaded hook and guide rod and align a pin with a cam surface, locking the filter in place. The hook and guide rod design presently used is susceptible to malfunction due to incomplete engagement between the pin and the cam surface, differences in the spring strength and length, and the force of the fluid passing through the filter.
Maintaining the filters within a purification system is also important to the continued efficient operation of a power plant. Typical maintenance involves reconnecting filters which have become disconnected or have been forced from their connection by the pressure of the fluid passing through them, and requires the purification system to be temporarily shut down during reconnection. Because of the proximity of each filter within the purification system, it is difficult and time consuming to reconnect presently used filters.
In addition to the importance of quickly and easily connecting the filters, and of maintaining that connection, it is important to be able to recover used filters by backwashing fluid through them to remove the impurities that have been filtered out. After continued use, the filter will become filled with particles, and the filter will become unable to purify fluid. To prolong the life of the individual filters and delay their replacement, the flow of fluid within the purification system can be reversed to backwash the filters and remove the debris collected by the filters. However, by reversing the flow of fluid through the purification system, the filters are subjected to a force directed in the opposite direction of the force of filtering. This reverse force can negatively affect the individual filters, forcing them from their connections and requiring the system to be shut down until the filters are reconnected.
Individual filters can also be treated to attract ions that may not be captured by the physical structure of the filter. Backwashing is also important to remove filter treatments saturated with attracted impurities.
For the reasons described above, the presently used filters are susceptible to a variety of malfunctions due to becoming disconnected during backwashing, installation error, and defects or variations in the connecting mechanism. Accordingly, there is an unmet need for a more reliable means of attaching and securing a filter cartridge within a filter system, so that the filter cartridge will not be affected by increased pressure or the reversal of fluid flow associated with backwashing or cleaning of the purification system. In addition, due to the number of filters within a purification system, there is an unmet need for an improved coupling mechanism providing an easy and efficient means of attaching or removing a filter from the system, thus providing a means of reducing downtime in the apparatus utilizing the present filter system. Finally, there is a need for a filter system incorporating an improved filter element having improved filtration capacity due to the improved coupling mechanism.